Entry: ho·lo·caust
Pronunciation: 'hO-l&-"kost, 'hä- also -"käst or 'ho-l&-kost
Function: noun
Etymology: Middle English, from Old French holocauste, from Late Latin holocaustum, from Greek holokauston, from neuter of holokaustos burnt whole, from hol- + kaustos burnt, from kaiein to burn -- more at CAUSTIC
1 : a sacrifice consumed by fire
2 : a thorough destruction involving extensive loss of life especially through fire
3 a often capitalized : the mass slaughter of European civilians and especially Jews by the Nazis during World War II -- usually used with the b : a mass slaughter of people; especially : GENOCIDE

把这段解释和无名练箭的大作中引用的联合国关于种族灭绝罪的convention定义对照来看，张用holocaust显然没有用错，而且用的是GENOCIDE的含义。